Portable parts washer systems, which have solvent recirculating subsystems, are well known in the art and are used for cleaning and decontamination processes of dirty, greasy parts and tools. Such systems and widely accepted in industries ranging from typewriter repair to aircraft maintenance shops. The patented art is replete with examples of parts washer systems. Most include a sink or drain pan which is mounted atop a cart or table for washing parts or work pieces therein. A solvent supply hose is directed over the parts by an operator. The resulting used solvent is contained in the sink which drains into a solvent supply tank. A pump is used for recirculating the solvent to the solvent supply hose. In order to increase the effectiveness of the recirculated solvent, many of the systems are provided with a filter for removing bulk contaminants from the solvent before it is reused.
The efficiency of these systems, however, is particularly lacking where the processing of the particular parts or work pieces require the application of multiple fluids. For example, in the aerospace industry, it is often desirable to apply a coating to a work piece for surface preparation purposes. Such a coating may be a conversion coating which is an intermediate coating for corrosion prevention. In practice, the conversion coating is applied to a part. Subsequently, the coated part is rinsed with a second fluid, such as water, to remove any excess conversion coating material. It is desirable to recirculate or recycle both the excess or used conversion coating fluid and the rinsing fluid as these fluids are treated as waste material when no longer effective for their intended use. Because of safety and regulatory reasons the fluid waste material must be specially handled and disposed of. Effective recirculation of the resulting fluids caught in the sink or drain pan of a prior art system, as described above, is significantly inefficient. Because the resulting fluid which is caught in a common drain pan, recycling of the fluid for use as the coating fluid is undesirable as it is quickly diluted by the rinse fluid. Conversely, recycling of the fluid for use as the rinse fluid is undesirable as it quickly contaminated with the coating fluid. In addition, where the coating and rinse fluids are chemically reactive, any such reaction may result in a degradation of the particular fluid's effectiveness.
While the prior art parts washers include recirculation systems which employ filtering devices, such filtering is limited to bulk contaminants, as is the case with degreasing dirty parts. Thus, filtering is simply accomplished by screening particulate matter from the recirculated fluid. Such a filtering scheme is ineffective in the case, described above, where two fluids are utilized. This is because the contaminant of interest is not a bulk material or particulate, but rather each fluid represents a contaminant to the other.
Another common example of where multiple fluids are utilized and recirculation of such fluids is desirable is where a part needs to undergo a surface preparation process for adhesion purposes. In this respect, a part may be exposed to an acidic or etchant solution which roughens the surface of the part. Thus, this processing facilitates improved adhesion of a subsequently applied coating, such as paint for example. During this process, after the acidic solution is applied, a second fluid is used to rinse the part of any excess solution as well as any dialoged material resulting from the acidic reaction with the part. Again, as in the conversion coating process, effective recirculation of the resulting fluids caught in the drain pan of a prior art system, as described above, is significantly inefficient. Because the resulting fluid which is caught in a common drain pan, recycling of the fluid for use as the acid solution is undesirable as it may be quickly diluted by the rinse fluid. Conversely, recycling of the fluid for use as the rinse fluid is undesirable as it may quickly become contaminated with the acid solution.
It is recognized that safety and environmental protection regulations are becoming a focus of attention. As such, it is therefore evident that there exists a need in the art for a multi-fluid system which facilitates the application of multiple fluids which are recirculated for improved effective reuse of the fluids prior to their disposal.